Light sensor

ABSTRACT

A first substrate includes a plurality of unit pixel regions. A deep trench isolation structure is disposed in the first substrate and isolates each of the plurality of the unit pixel regions from each other. Each of a plurality of photoelectric converters is disposed in one of the plurality of unit pixel regions. A plurality of micro lenses are disposed on the first substrate. A plurality of light splitters are disposed on the first substrate. Each of the plurality of light splitters is disposed between one of the plurality of micro lenses and one of the plurality of photoelectric converters. Each of a plurality of photoelectric-conversion-enhancing layers is disposed between one of the plurality of light splitters and one of the plurality of photoelectric converters.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2016-0181310, filed on Dec. 28, 2016, in the KoreanIntellectual Property Office, the disclosure of which is incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present inventive concept relates to a light sensor.

DISCUSSION OF RELATED ART

Infrared light is electromagnetic waves whose wavelengths are longerthan those of visible light, and are in a range of about 0.75 μm toabout 1000 μm. Infrared light may be classified into three regions ofnear-infrared (0.75 μm to 1.5 μm), mid-infrared (1.5 μm to 5.6 μm), andfar-infrared (5.6 μm to 1000 μm). The wavelength of near-infrared lightis longer than that of visible light, and thus the quantum efficiency ofphotoelectric converters of light sensors using near-infrared light maybe very low.

SUMMARY

According to an exemplary embodiment of the present inventive concept, alight sensor is provided as follows. A first substrate includes aplurality of unit pixel regions. A deep trench isolation structure isdisposed in the first substrate and isolates each of the plurality ofunit pixel regions from each other. Each of a plurality of photoelectricconverters is disposed in one of the plurality of unit pixel regions. Aplurality of micro lenses are disposed on the first substrate. Aplurality of light splitters are disposed on the first substrate, witheach of the plurality of light splitters disposed between one of theplurality of micro lenses and one of the plurality of photoelectricconverters. Each of a plurality of photoelectric-conversion-enhancinglayers is disposed between one of the plurality of light splitters andone of the plurality of photoelectric converters.

According to an exemplary embodiment of the present inventive concept, alight sensor is provided as follows. A substrate having a first surfaceand a second surface opposite to the first surface includes a pluralityof unit pixel regions. A photoelectric converter is disposed in each ofthe plurality of unit pixel regions of the substrate. A micro lens isdisposed on the second surface of the substrate and overlaps one of theplurality of unit pixel regions. A light splitter is disposed betweenthe micro lens and the photoelectric converter. Aphotoelectric-conversion-enhancing layer is disposed between the lightsplitter and the photoelectric converter. The light splitter is disposedat a focal point of the micro lens.

According to an exemplary embodiment of the present inventive concept, alight sensor is provided as follows. A substrate has an array of aplurality of unit pixel regions including a first unit pixel region anda second unit pixel region. Each of the plurality of unit pixel regionsincludes a photoelectric converter. A plurality of light splitters,including a first light splitter and a second light splitter, isdisposed on the substrate. The first light splitter is disposed at afirst distance from the center of the first unit pixel region and thesecond light splitter is disposed at a second distance from the centerof the second unit pixel region. The second distance is larger than thefirst distance. A plurality of micro lens includes a first micro lensand a second micro lens that overlaps the first light splitter and thesecond light splitter, respectively. The center of the first micro lensand the center of the second micro lens are directly above the center ofthe first unit pixel region and the center of the second unit pixelregion, respectively.

BRIEF DESCRIPTION OF DRAWINGS

These and other features of the present inventive concept will becomemore apparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings of which:

FIG. 1 is a schematic diagram illustrating an image processing deviceaccording to an exemplary embodiment of the present inventive concept;

FIG. 2 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 3 is a cross-sectional view illustrating a path of light in thelight sensor of FIG. 2 according to an exemplary embodiment of thepresent inventive concept;

FIGS. 4A and 4B are cross-sectional views illustrating light sensorsaccording to an exemplary embodiment of the present inventive concept;

FIG. 5 is a plan view illustrating a light sensor according to anexemplary embodiment of the present inventive concept;

FIGS. 6 to 9 are plan views illustrating planar shapes of lightsplitters according to an exemplary embodiment of the present inventiveconcept;

FIGS. 10 to 15 are cross-sectional views illustrating a method ofmanufacturing the light sensor of FIG. 2 according to an exemplaryembodiment of the present inventive concept;

FIG. 16 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 17 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 18 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 19 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 20 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIGS. 21 and 22 are cross-sectional views illustrating a method ofmanufacturing the light sensor of FIG. 20 according to an exemplaryembodiment of the present inventive concept;

FIG. 23 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 24 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 25 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 26 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 27 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 28 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 29 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 30 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 31 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 32 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 33 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIG. 34 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept;

FIGS. 35 and 36 are circuit diagrams illustrating light sensorsaccording to an exemplary embodiment of the present inventive concept;and

FIG. 37 is a schematic block diagram illustrating a light sensoraccording to an exemplary embodiment of the present inventive concept.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the present inventive concept will be describedbelow in detail with reference to the accompanying drawings. However,the inventive concept may be embodied in different forms and should notbe construed as limited to the embodiments set forth herein. In thedrawings, the thickness of layers and regions may be exaggerated forclarity. It will also be understood that when an element is referred toas being “on” another element or substrate, it may be directly on theother element or substrate, or intervening layers may also be present.It will also be understood that when an element is referred to as being“coupled to” or “connected to” another element, it may be directlycoupled to or connected to the other element, or intervening elementsmay also be present. Like reference numerals may refer to the likeelements throughout the specification and drawings.

The values such as thickness and width of a constituent element may beexpressed using “substantially the same” or “about”, because the valuesmeasured in an image sensor device fabricated according to the presentinventive concept may be different from the exact value claimed belowdue to a process variation for forming the image sensor device or due toa measurement error.

FIG. 1 is a schematic diagram illustrating an image processing deviceaccording to an exemplary embodiment of the present inventive concept.

In FIG. 1, the image processing device 1000 may include a lens 1001transmitting light generated from an object, a light sensor 1003 sensingthe light transmitted from the lens 1001, and a display part 1005displaying image data generated from the light sensor 1003. In anexemplary embodiment, the light sensor 1003 may sense infrared lightother than visible light. In this case, the image processing device 1000may also include an infrared filter disposed on a surface of the lens1001 or between the lens 1001 and the light sensor 1003 to transmit onlythe infrared light generated from the object. In another exemplaryembodiment, the light sensor 1003 may sense visible light. In this case,the image processing device 1000 may not include the infrared filter.The light sensor 1003 may include a circuit part that stores andprocesses electrical signals converted from infrared light receivedthrough the lens 1001. In an exemplary embodiment, the circuit part maybe provided as an additional device separated from the light sensor 1003and may be connected between the light sensor 1003 and the display part1005.

FIG. 2 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 2, a light sensor 100 may include a substrate 1 including aplurality of unit pixel regions UP. The substrate 1 may include asingle-crystalline silicon substrate, a silicon-on-insulator (SOI)substrate, or a silicon epitaxial layer. The substrate 1 may include afirst surface 1 a (or a bottom surface) and a second surface 1 b (or atop surface) opposite to each other. Infrared light may be incident onthe second surface 1 b.

Circuits may be disposed on the first surface 1 a. A shallow trenchisolation layer STI may be disposed at the first surface 1 a to definean active region. For example, the shallow trench isolation layer STImay extend from the first surface 1 a into the substrate 1.

A device isolation region doped with impurities may be disposed insideof the shallow trench isolation layer STI.

The unit pixel regions UP may be isolated from each other by a deeptrench isolation structure DTI. The deep trench isolation structure DTImay penetrate the substrate 1 between the first surface 1 a of thesubstrate 1 and the second surface 1 b of the substrate 1. The deeptrench isolation structure DTI may have a mesh shape when viewed in aplan view. For example, the deep trench isolation structure DTI maysurround each of the plurality of unit pixel regions UP. The lightsensor 100 may include the deep trench isolation structure DTI isolatingthe plurality of unit pixel regions UP from each other to preventcrosstalk between adjacent unit pixel regions UP. For example, withoutthe deep trench isolation structure DTI according to an exemplaryembodiment, infrared light coming into one of the plurality of unitpixel regions UP may enter another unit pixel region or may be reflectedto enter another unit pixel region adjacent to the one of the pluralityof unit pixel regions UP receiving the infrared light.

The deep trench isolation structure DTI may include an insulatingmaterial layer such as a silicon oxide layer, a silicon nitride layer, asilicon oxynitride layer, or a combination thereof. In addition, thedeep trench isolation structure DTI may include a poly-silicon patterndisposed therein. A voltage may be applied to the poly-silicon patternto reduce dark current and prevent a white spot from being displayed onthe display part 1005 of FIG. 1.

A first impurity injection region 8 and a second impurity injectionregion 4 may be disposed in the substrate 1. The first impurityinjection region 8 may be doped with impurities of a first conductivitytype, and the second impurity injection region 4 may be doped withimpurities of a second conductivity type different from the firstconductivity type. For example, the first impurity injection region 8may be doped with P-type impurities, and the second impurity injectionregion 4 may be doped with N-type impurities. The first impurityinjection region 8 and the second impurity injection region 4 mayconstitute a photoelectric converter (e.g., a photodiode). In anexemplary embodiment, the second impurity injection region 4 may besurrounded by the first impurity injection region 8.

A transfer gate TG, a floating diffusion region FD, and a ground region12 may be disposed at the first surface 1 a. The transfer gate TG mayhave a vertical-type gate shape that includes a portion extending intothe substrate 1. In an exemplary embodiment, the transfer gate TG mayhave a flat-type gate shape that is disposed on the first surface 1 a ofthe substrate 1. A gate insulating layer 10 may be disposed between thetransfer gate TG and the substrate 1. The floating diffusion region FDmay be doped with impurities of the same conductivity type as the secondimpurity injection region 4. For example, the floating diffusion regionFD may be doped with N-type impurities. The ground region 12 may bedoped with impurities of the same conductivity type as the firstimpurity injection region 8, and the doping concentration of theimpurities of the ground region 12 may be higher than that of theimpurities of the first impurity injection region 8.

When a voltage is applied to the transfer gate TG, a transistorincluding the transfer gate TG may be turned-on to transfer chargesgenerated in the first impurity injection region 8 and the secondimpurity injection region 4 into the floating diffusion region FD. Thecharges accumulated in the floating diffusion region FD may betransmitted to the outside of the unit pixel region UP by othertransistors (e.g., a source follower transistor, a reset transistor, anda selection transistor) or interconnection lines, or a combinationthereof.

An interlayer insulating layer 20 and interconnection lines 22 may bedisposed on the first surface 1 a. The interlayer insulating layer 20may be covered with a passivation layer 28. A first reflector 25 may bedisposed in the interlayer insulating layer 20. The first reflector 25may have a flat plate shape occupying a considerable portion of each ofthe plurality of unit pixel regions UP when viewed in a plan view orviewed from the above of the light sensor 100. In an exemplaryembodiment, infrared light incoming into one of the plurality of pixelregions UP through the second surface 1 b may travel to the interlayerinsulating layer 20, and the first reflector 25 may reflect the infraredlight to re-enter the same pixel region UP where the infrared lightenters. Accordingly, the first reflector 25 may have an area sufficientthat the first reflector 25 may prevent the infrared light arriving atthe interlayer insulating layer 20 from passing through the interlayerinsulating layer 20.

The first reflector 25 may be formed of a portion of the interconnectionlines 22. In this case, the first reflector 25 may be part of a signalpath formed by the interconnection lines 22. In an exemplary embodiment,the first reflector 25 may be formed in an additional metal layerseparated from the interconnection lines 22. In this case, the firstreflector 25 need not be part of a signal path formed by theinterconnection lines 22.

A recess region 32 may be formed in the substrate 1 by recessingpartially the second surface 1 b toward the first surface 1 a. Asidewall of the recess region 32 may form an obtuse angle with thesecond surface 1 b. An entrance of the recess region 32 may be widerthan a bottom surface of the recess region 32.

A fixed charge layer 40 may be disposed on the second surface 1 b. Thefixed charge layer 40 may be in contact with the substrate 1 and mayconformally cover an inner surface of the recess region 32. The fixedcharge layer 40 may include a metal oxide layer containing insufficientoxygen in terms of a stoichiometric ratio or a metal fluoride layercontaining insufficient fluorine in terms of a stoichiometric ratio.Thus, the fixed charge layer 40 may have negative fixed charges. Thefixed charge layer 40 may include a metal oxide layer or metal fluoridelayer including at least one of hafnium (Hf), zirconium (Zr), aluminum(Al), tantalum (Ta), titanium (Ti), yttrium (Y), and a lanthanoid (Ln).For example, the fixed charge layer 40 may be a hafnium oxide layer oran aluminum fluoride layer. In the fixed charge layer 40 adjacent to thesecond surface 1 b, holes may be accumulated. Thus, dark current and anywhite spots may be effectively reduced. For example, when infrared lightpasses through the first impurity injection region 8 and the secondimpurity injection region 4 (collectively referred to as a photoelectricconverter or a photodiode), a plurality of electron-hole pairs may begenerated in the first impurity injection region 8 and the secondimpurity injection region 4. In this case, the holes of the plurality ofelectron-hole pairs may be accumulated in the fixed charge layer 40; andthe electrons of the plurality of electron-hole pairs may be accumulatedin the floating diffusion region FD.

A light splitter 35 may be disposed in the recess region 32 whose innersurface is conformally covered with the fixed charge layer 40. The lightsplitter 35 may be in contact with the fixed charge layer 40. In anexemplary embodiment, the light splitter 35 may be formed of a materialhaving a different refractive index from the substrate 1. For example,the light splitter 35 may be formed of a material whose refractive indexis lower than a refractive index of silicon of the substrate 1. Forexample, the light splitter 35 may include at least one of a siliconoxide layer, a silicon nitride layer, a silicon oxynitride layer, and ametal oxide layer. A top surface of the light splitter 35 may besubstantially coplanar with a top surface of the fixed charge layer 40disposed on the second surface 1 b at substantially the same height fromthe first surface 1 a of the substrate 1. The sidewall of the recessregion 32 may be spaced apart from the deep trench isolation structureDTI. In an exemplary embodiment, the light splitter 35 may be providedin plural. For example, each of the plurality of pixel regions UP mayeach have one light splitter 35.

An anti-reflection layer 42 may cover the fixed charge layer 40 and thelight splitter 35. For example, the anti-reflection layer 42 may includea silicon nitride layer.

A planarization layer 44 may be disposed on the anti-reflection layer42. The planarization layer 44 may include a silicon oxide layer or aphotoresist layer not including a pigment. In an exemplary embodiment,the planarization layer 44 may include a pigment. When a pigment isincluded, a color filter need not be present in the light sensor 100.The planarization layer 44, when including a pigment, may serve as acolor filter instead of a separate color filter element.

A plurality of micro lenses 46 may be disposed on the planarizationlayer 44. Each of the plurality of micro lenses 46 may be disposed onone of the plurality of unit pixel regions UP.

When an infrared filter is disposed between the lens 1001 and the lightsensor 1003 of FIG. 1 senses infrared light through the light sensor100, the light sensor 100 does not require a color filter to filter aspecific color of light. In this case, the planarization layer 44 doesnot require a pigment or a color filter. Even when a color filter isdisposed on the planarization layer 44, or when the planarization layer44 includes a pigment, the infrared light may pass through the colorfilter or the planarization layer 44 with a pigment, as the infraredlight may be unaffected by color filtering due to its longer wavelength.

FIG. 3 is a cross-sectional view illustrating a path of light in thelight sensor of FIG. 2.

In FIG. 3, light L may travel to the light splitter 35 through the microlens 46. Since a surface of the micro lens 46 is convex, the light L maybe focused at one spot (a focal point FP). The light splitter 35 may bedisposed at the spot where the light L is focused. For example, thelight splitter 35 may be disposed at the focal point FP of the microlens 46. Infrared light or red light included in the light L may have alow absorption factor in the substrate 1 because of its long wavelength.In other words, the infrared light or red light of the light L may passthrough the substrate 1 having a lower chance to generate anelectron-hole pair. As such, the quantum efficiency of infrared light orred light may be lower compared to other, shorter wavelength, visiblelight of the light L. The quantum efficiency includes the rate at whichlight is converted into charge.

In an exemplary embodiment, the light sensor 100 may include the lightsplitter 35, and thus the light L may be scattered and split into aplurality of rays at an interface between the light splitter 35 and thesubstrate 1. The plurality of rays of the light L may travel through aplurality of paths, respectively, so that each of the plurality of raysof the light L may have an increased light path (represented by dashedlines, for example) by being reflected by the deep trench 3. Forexample, the plurality of paths may include reflections, such as off thedeep trench isolation structure DTI surrounding each of the plurality ofunit pixel regions UP. The increased path of the plurality of rays mayinclude reflection by a shallow trench isolation layer STI or the firstreflector 25. Thus, the scattering of the light L by the light splitter35 may induce multiple reflections to increase the light path within theunit pixel region UP. As a result, the absorption factor of, e.g., theinfrared light or red light may increase in the light sensor 100, andthe quantum efficiency of the infrared light or red light may increasein the light sensor 100.

The first reflector 25 may reflect the light L, which is incident intothe interlayer insulating layer 20, into the substrate 1 to increase theabsorption factor of the light L.

FIGS. 4A and 4B are cross-sectional views illustrating light sensorsaccording to an exemplary embodiment of the present inventive concept.FIG. 5 is a plan view illustrating a light sensor according to anexemplary embodiment of the present inventive concept.

In an exemplary embodiment, depending on the location of each of theplurality of unit pixel regions UP in the light sensor 100, each of theplurality of unit pixel regions UP may have different cross-sectionalstructure, as shown in FIGS. 3 and 4A, and 5. For example, FIG. 4A showsa cross-sectional view of a unit pixel region UP positioned in an edgeregion ED of FIG. 5; and FIG. 3 shows a cross-sectional view of a unitpixel region UP positioned in a central region CT of FIG. 5.

If light is vertically incident on the top surface of the substrate 1 ina central region CT of the light sensor 100, the light passing throughthe micro lens 46 may be focused at a central portion of the unit pixelregion UP in the central region CT of the light sensor 100. Thus, thelight splitter 35 may be disposed at the central portion of the unitpixel region UP as illustrated in FIG. 3.

If light is incident obliquely (e.g., at a low angle) in an edge regionED of the light sensor 100, the light passing through the micro lens 46may be focused at an edge portion of the unit pixel region UP in theedge region ED of the light sensor 100 as illustrated in FIG. 4A. Thus,the light splitter 35 may be disposed adjacent to the deep trenchisolation structure DTI in the unit pixel region UP in the edge regionED of the light sensor 100. In an exemplary embodiment, as illustratedin FIG. 4B, the position of the light splitter 35 may be fixed at thecentral portion of the unit pixel region UP in the edge region ED, andthe position of the micro lens 46 may be laterally shifted toconcentrate light passing through the micro lens 46 to the lightsplitter 35. For example, in each of the unit pixel regions UP, thelight splitter 35 may be disposed at the spot where light passingthrough the micro lens 46 is focused, as illustrated in FIG. 5.

In FIG. 5, the light sensor 100 may include an array AUPR of a pluralityof unit pixel regions UP including a first unit pixel region UP-1 and asecond unit pixel region UP-2. Each of the plurality of unit pixelregions UP may include a photoelectric converter including the firstimpurity injection region 8 and the second impurity injection region 4of FIG. 2. A plurality of light splitters 35 may be disposed on thesubstrate 1 of FIG. 2. The plurality of light splitters 35 may include afirst light splitter 35-1 and a second light splitter 35-2. The firstlight splitter 35-1 may be disposed at a first distance from the centerof the first unit pixel region UP-1 and the second light splitter 35-2may be disposed at a second distance from the center of the second unitpixel region UP-2. The second distance is larger than the firstdistance. Each of the plurality of micro lens 46 may have a center thatis directly above the center of each of the plurality of unit pixelregions UP. (See FIGS. 2 and 34, for example).

In an exemplary embodiment of the present inventive concept, the firstunit pixel region UP-1 and the first light splitter 35-1 may be arrangedas shown in FIG. 2. In this case, the first distance may besubstantially zero so that the first light splitter 35-1 is disposeddirectly under the center of the first micro lens and at a focal pointFP of the first micro lens, as shown in FIG. 2. The second unit pixelregion UP-2 and the second light splitter 35-2 may be arranged as shownin FIG. 4A. In this case, the second distance may be greater than zero.

FIGS. 6 to 9 are plan views illustrating planar shapes of lightsplitters according to an exemplary embodiment of the present inventiveconcept.

In FIGS. 6 to 9, the light splitter 35 may have at least one of variousplanar shapes. For example, the light splitter 35 may have a squareplanar shape like FIG. 6 or may have a cross planar shape like FIG. 7.In an exemplary embodiment, the light splitter 35 may have a lozengeplanar shape like FIG. 8, or may have a circular planar shape like FIG.9. However, the present inventive concept is not limited thereto. Theplanar shape of the light splitter 35 may have various shapes.

A method of manufacturing the light sensor of FIG. 2 will be describedhereinafter.

FIGS. 10 to 15 are cross-sectional views illustrating a method ofmanufacturing the light sensor 100 of FIG. 2.

In FIG. 10, a deep trench isolation structure DTI may be formed in asubstrate 1 having a first surface 1 a and a second surface 1 b oppositeto each other, thereby isolating each of the plurality of unit pixelregions UP from each other. Now, a bottom surface of the deep trenchisolation structure DTI may be spaced apart from the second surface 1 b.The substrate 1 may be partially etched to form a deep trench 3, and aninsulating material may be formed to fill the deep trench 3. Aplanarization process may be performed on the insulating material toform the deep trench isolation structure DTI. The deep trench isolationstructure DTI may include at least one of a silicon oxide layer, asilicon nitride layer, and a silicon oxynitride layer. The deep trenchisolation structure DTI may be formed in a mesh shape when viewed in aplan view so that the deep trench isolation structure DTI surrounds eachof the plurality of unit pixel regions UP.

Next, ion implantation processes may be performed to form a firstimpurity injection region 8 and a second impurity injection region 4 inthe substrate 1 of each of the unit pixel regions UP isolated from eachother by the deep trench isolation structure DTI.

A shallow trench isolation layer STI may be formed in the substrate 1adjacent to the first surface 1 a to define active regions. Portions ofthe substrate 1 surrounded by the deep trench isolation structure DTImay be partially removed to form a shallow trench, and the shallowtrench isolation layer STI may be formed by filling the shallow trenchwith a filling insulation layer.

In FIG. 11, a portion of the substrate 1 exposed by the shallow trenchisolation layer STI may be etched to form a recessed region, and athermal oxidation process or a deposition process may be performed toform a gate insulating layer 10 conformally covering an inner surface ofthe recessed region and a surface (e.g., the top surface) of thesubstrate 1. A conductive layer may be formed to fill the recessedregion, and a patterning process may be performed on the conductivelayer to form a transfer gate TG. Even though not shown in the drawings,other gates having other functions may also be formed when the transfergate TG is formed.

Ion implantation processes may be performed to form a floating diffusionregion FD and a ground region 12 in the substrate 1 of each of the unitpixel regions UP. In an exemplary embodiment, the ion implantationprocesses may be performed after the formation of the transfer gate TGand the shallow trench isolation layer STI.

Interconnection lines 22, contact plugs, first reflectors 25, and aninterlayer insulating layer 20 may be formed on the first surface 1 a.The interlayer insulating layer 20 may cover or surround theinterconnection lines 22, the contact plugs, and the first reflectors25.

A passivation layer 28 may be formed on the interlayer insulating layer20. The passivation layer 28 may be formed of a silicon nitride layer ora polyimide layer, or both.

In FIG. 12, the substrate 1 may be turned over such that the secondsurface 1 b may face upward. A back grinding process may be performed onthe second surface 1 b to remove a portion of the substrate 1 until thedeep trench isolation structure DTI is exposed. In an exemplaryembodiment, once the deep trench isolation structure DTI is exposed, theback grinding process may be further performed for a predetermined timeto ensure that the deep trench isolation structure DTI is entirelyexposed.

In FIG. 13, a mask pattern 30 may be formed on the second surface 1 b.For example, the mask pattern 30 may include silicon nitride. The secondsurface 1 b may be etched using the mask pattern 30 as an etch mask toform a recess region 32 in the substrate 1 of each of the unit pixelregions UP.

In FIG. 14, the mask pattern 30 may be removed to expose the secondsurface 1 b. The fixed charge layer 40 may be conformally formed on thesecond surface 1 b to cover a sidewall and a bottom surface of therecess region 32. A low refractive index layer 34 may be formed on thefixed charge layer 40 to fill the recess region 32. The low refractiveindex layer 34 may be formed of a material having a lower refractiveindex than silicon. For example, the low refractive index layer 34 maybe formed of at least one of a silicon oxide layer, a silicon nitridelayer, a silicon oxynitride layer, and a metal oxide layer.

In FIG. 15, a planarization etching process may be performed on the lowrefractive index layer 34 to expose the fixed charge layer 40 disposedon the second surface 1 b and to form a light splitter 35 in the recessregion 32. For example, the light splitter 35 may correspond to the lowrefractive index layer 34 that remains in the recess region 32 after theplanarization etching process is performed on the low refractive indexlayer 34.

Referring again to FIG. 2, an anti-reflection layer 42 and aplanarization layer 44 may be sequentially formed on the second surface1 b. In an exemplary embodiment, the anti-reflection layer 42 and theplanarization layer 44 may be formed on the entire surface of the secondsurface 1 b of each unit pixel region UP. A micro lens 46 may be formedon the planarization layer 44.

In the present embodiment, the deep trench isolation structure DTI maybe first formed before the formation of the constituent elements on thefirst surface 1 a of the substrate 1. However, the present inventiveconcept is not limited thereto. For example, the constituent elements onthe first surface 1 a including shallow trench isolation layers STI,transistors and interconnection lines may be first formed on the firstsurface 1 a, and then, the back grinding process may be performed on thesecond surface 1 b. Thereafter, a portion of the substrate 1 may beetched from the second surface 1 b to form a deep trench 3, and the deeptrench isolation structure DTI may be formed by filling the deep trench3 with an insulating layer. In this example, before the deep trench 3 isfilled with the insulating layer, the recess region 32 may be formed inthe substrate 1 adjacent to the second surface 1 b and the fixed chargelayer 40 may be conformally formed. In this case, the fixed charge layer40 may conformally cover a sidewall and a bottom surface of the deeptrench 3 as well as the sidewall and the bottom surface of the recessregion 32.

FIG. 16 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 16, a light sensor 101 may include a light splitter 36. Thelight splitter 36 may be a portion of a substrate 1, which protrudesfrom a second surface 1 b of the substrate 1. A lower portion of thelight splitter 36 may be wider than an upper portion of the lightsplitter 36. A sidewall of the light splitter 36 may be inclined. Thesecond surface 1 b may be lower than a top surface of the deep trenchisolation structure DTI, and a portion of a sidewall of the deep trenchisolation structure DTI may be exposed from the second surface 1 b.

The fixed charge layer 40 may conformally cover the portion of thesidewall and the top surface of the deep trench isolation structure DTI,the second surface 1 b, and the sidewall and a top surface of the lightsplitter 36.

A refractive index difference part 37 may be disposed between the fixedcharge layer 40 and an anti-reflection layer 42. In an exemplaryembodiment, the refractive index difference part 37 may be formed of amaterial having a different refractive index from the substrate 1. Forexample, the refractive index difference part 37 may be formed of amaterial having a lower refractive index than silicon. For example, therefractive index difference part 37 may be formed of at least one of asilicon oxide layer, a silicon nitride layer, a silicon oxynitridelayer, and a metal oxide layer.

The other components of the light sensor 101 of the present embodimentmay be the same or similar as corresponding components of the lightsensor 100 of FIG. 2. As described with reference to FIG. 2, lightpassing through the micro lens 46 may be scattered at the sidewall ofthe light splitter 36 in the light sensor 101. At least one of the deeptrench isolation structure DTI, the first reflector 25, and the shallowtrench isolation layer STI may serve as a reflector of the light passingthrough the micro lens 46. Thus, multiple reflections may be induced toincrease the light path within the sensor. As a result, the lightabsorption factor of the light sensor 101 may increase.

The light sensor 101 of FIG. 16 may be manufactured by a similar methodto the method of manufacturing the light sensor 100 of FIG. 2. The shapeof the mask pattern 30 may be changed in FIG. 13. For example, the maskpattern 30 of FIG. 13 may be formed to cover a position, where the lightsplitter 36 of FIG. 16 will be formed, but to expose the remainingregion of the substrate 1. The substrate 1 may be etched using the maskpattern 30 as an etch mask to form the light splitter 36 correspondingto a protruding portion of the substrate 1 and to expose a portion ofthe sidewall of the deep trench isolation structure DTI. Subsequently,the fixed charge layer 40 may be conformally formed. Next, a lowrefractive index layer may be formed to fill a space between the lightsplitter 36 and the deep trench isolation structure DTI, and aplanarization etching process may be performed on the low refractiveindex layer to form the refractive index difference part 37. The othermanufacturing processes may be the same or similar as described withreference to FIGS. 10 to 15.

FIG. 17 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 17, a light sensor 102 may include a deep trench isolationstructure DTI extending from the second surface 1 b toward the firstsurface 1 a of the substrate 1 but need not be in contact with the firstsurface 1 a.

In FIG. 17, the fixed charge layer 40 may be formed to cover a topsurface of the deep trench isolation structure DTI. Even though notshown in the drawings, a poly-silicon pattern may be disposed within thedeep trench isolation structure DTI, and a voltage may be applied to thepoly-silicon pattern. In an exemplary embodiment, the fixed charge layer40 may also extend onto an inner surface of the deep trench 3 in whichthe deep trench isolation structure DTI is disposed. The othercomponents of the light sensor 102 may be the same or similar ascorresponding components of the light sensor 100 described withreference to FIG. 2.

A method of manufacturing the light sensor 102 may be similar to themethod of manufacturing the light sensor 100 of FIG. 2. However, thedeep trench isolation structure DTI may be formed after performing theback grinding process on the second surface 1 b. At this time, the deeptrench 3 may extend from the second surface 1 b toward the first surface1 a and may be spaced apart from the first surface 1 a. The othermanufacturing processes may be the same or similar as described withreference to FIGS. 10 to 15.

FIG. 18 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 18, a light sensor 103 may include a deep trench isolationstructure DTI including a second insulating part 5 conformally formedalong an inner surface of a deep trench 3, and a second reflector 7being in contact with the second insulating part 5 and filling the deeptrench 3. The second reflector 7 may reflect light, which is incident onthe sidewall of the deep trench isolation structure DTI, into thesubstrate 1 to increase the absorption factor of light. In addition, avoltage may be applied to the second reflector 7 to reduce a darkcurrent or a white spot within the light sensor 103. The othercomponents of the light sensor 103 may be the same or similar ascorresponding components of the light sensor 100 of FIG. 2. In a methodof manufacturing the light sensor 103, an insulating layer may beconformally formed after the formation of the deep trench 3 in the stepof FIG. 10 and a metal layer may be formed to fill the deep trench 3.Subsequently, a planarization etching process may be performed to formthe second insulating part 5 and the second reflector 7 constituting thedeep trench isolation structure DTI. The other manufacturing processesmay be the same or similar as described with reference to FIGS. 10 to15.

FIG. 19 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 19, a light sensor 104 may include a deep trench isolationstructure DTI including a first insulating part 6 partially extendingfrom the first surface 1 a toward the second surface 1 b, a secondinsulating part 5 partially extending from the second surface 1 b towardthe first surface 1 a, and a second reflector 7 disposed in the secondinsulating part 5. The other components of the light sensor 104 may bethe same or similar as corresponding components of the light sensor 103described with reference to FIG. 18. In a method of manufacturing thelight sensor 104, the substrate 1 may be partially etched from the firstsurface 1 a toward the second surface 1 b to form a portion of a deeptrench 3, and the first insulating part 6 may be formed by filling theportion of the deep trench 3 with an insulating layer. Subsequently, theback grinding process may be performed on the second surface 1 b, andthen, the substrate 1 may be partially etched from the second surface 1b toward the first surface 1 a to form another portion of the deeptrench 3. An insulating layer and a metal layer may be sequentiallyformed on the second surface 1 b and in another portion of the deeptrench 3, and a planarization etching process may be performed on themetal layer and the insulating layer to form the second reflector 7 andthe second insulating part 5. In this case, the second reflector 7 maybe formed of metal. The other manufacturing processes may be the same orsimilar as described with reference to FIGS. 10 to 15.

FIG. 20 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 20, a light sensor 105 may include a light splitter 50 that isdisposed on an anti-reflection layer 42. In this case, the lightsplitter 50 may be in contact with a planarization layer 44. Forexample, the light splitter 50 may be disposed between theanti-reflection layer 42 and the planarization layer 44. The lightsplitter 50 may include a material having a different refractive indexfrom the substrate 1. For example, the light splitter 50 may include amaterial whose refractive index is higher than a refractive index ofsilicon. The present inventive concept is not limited thereto. Forexample, the light splitter 50 may include a metal oxide layer having ahigher dielectric constant than a silicon oxide layer. The metal oxidelayer may be referred to as a high-k dielectric oxide. For example, themetal oxide layer may include at least one of a titanium oxide layer, ahafnium oxide layer, a lanthanum oxide layer, a zirconium oxide layer,and an aluminum oxide layer. Light incident through the micro lens 46may be scattered at an interface between the planarization layer 44 andthe light splitter 50. Thus, an absorption factor of light having a longwavelength (e.g., infrared light or red light) may be increased. Theother components of the light sensor 105 may be the same or similar ascorresponding components of the light sensor 100 of FIG. 2.

FIGS. 21 and 22 are cross-sectional views illustrating a method ofmanufacturing the light sensor of FIG. 20.

In FIG. 21, a fixed charge layer 40 and an anti-reflection layer 42 maybe sequentially formed on the second surface 1 b of the substrate 1. Ahigh refractive index layer 49 may be formed on the anti-reflectionlayer 42. The high refractive index layer 49 may be formed of a materialhaving a higher refractive index than silicon. For example, the highrefractive index layer 49 may be formed of at least one of a titaniumoxide layer, a hafnium oxide layer, a lanthanum oxide layer, a zirconiumoxide layer, and an aluminum oxide layer. A mask pattern 51 may beformed on the high refractive index layer 49. For example, the maskpattern 51 may be formed of silicon nitride.

In FIG. 22, the high refractive index layer 49 may be patterned usingthe mask pattern 51 as an etch mask to form a light splitter 50 and toexpose a surface of the anti-reflection layer 42.

Subsequently, referring again to FIG. 20, the mask pattern 51 may beremoved, and then, a planarization layer 44 may be formed on theanti-reflection layer 42 and the light splitter 50. A micro lens 46 maybe formed on the planarization layer 44.

FIG. 23 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 23, a light sensor 106 may include a light splitter 45 that maybe a portion of a planarization layer 44. The portion of theplanarization layer 44 may protrude toward the second surface 1 b of thesubstrate 1. A refractive index difference part 53 may be disposedbetween a bottom surface of the planarization layer 44 and theanti-reflection layer 42. A hole 52 may penetrate the refractive indexdifference part 53, and the light splitter 45 may be disposed in thehole 52. The refractive index difference part 53 may include a materialhaving a different refractive index from the substrate 1. For example,the refractive index difference part 53 may include a material whoserefractive index is higher than that of silicon. The refractive indexdifference part 53 may include a metal oxide layer having a higherdielectric constant than a silicon oxide layer. For example, therefractive index difference part 53 may include at least one of atitanium oxide layer, a hafnium oxide layer, a lanthanum oxide layer, azirconium oxide layer, and an aluminum oxide layer. The other componentsof the light sensor 106 may be the same or similar as correspondingcomponents of the light sensor 105 described with reference to FIG. 20.

A method of manufacturing the light sensor 106 may be similar to themethod of manufacturing the light sensor 105 of FIG. 20 using a maskpattern different from the shape of the mask pattern 51 of FIG. 21. Forexample, the shape of the mask pattern may be similar to the shape ofthe mask pattern 30 of FIG. 13 so that the mask pattern 51 may expose aportion of a preliminary refractive index difference part layer,covering a remaining portion of a preliminary refractive indexdifference part layer. The portion of the preliminary refractive indexdifferent part layer will be changed to the light splitter 45.Subsequently, the preliminary refractive index difference part layer maybe patterned using the mask pattern as an etch mask to form therefractive index difference part 53 having the hole 52 penetrating thepreliminary refractive index difference part layer. A planarizationlayer 44 may be formed on the refractive index difference part 53 tofill the hole 52, and thus the light splitter 45 may be formed in thehole 52. The other manufacturing processes may be the same or similar asdescribed with reference to FIGS. 21 and 22.

FIG. 24 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 24, a light sensor 107 may include a first light splitter 35 anda second light splitter 50 disposed on opposite sides of ananti-reflection layer 42. The first light splitter 35 may correspond tothe light splitter 35 of FIG. 2. The second light splitter 50 maycorrespond to the light splitter 50 of FIG. 20. The first light splitter35 may include a material having a lower refractive index than silicon.The second light splitter 50 may include a material having a higherrefractive index than silicon. The present inventive concept is notlimited thereto. For example, the first and second light splitters 35and 50 may be formed of the same material. The first light splitter 35and the second light splitter 50 may vertically overlap each other. Thecomponents of the light sensor 107 may be the same or similar ascorresponding components of the light sensors 100 and 105 described withreference to FIGS. 2 and 20. The first light splitter 35 may be formedby the same method as described with reference to FIGS. 13 to 15. Thesecond light splitter 50 may be formed by the same method as describedwith reference to FIGS. 21 and 22.

FIG. 25 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 25, a light sensor 108 may include a third impurity injectionregion 60 disposed in the substrate 1 close to the second surface 1 b.The third impurity injection region 60 may be doped with, for example,germanium (Ge). In this case, the third impurity injection region 60 mayincrease the photoelectric conversion efficiency of the photoelectricconverter including the first impurity injection region 8 and the secondimpurity injection region 4 due to an energy band gap of germaniumsmaller than an energy band gap of silicon. A small amount of lightincident may generate electron-hole pairs with the addition of the thirdimpurity injection region 60. In an exemplary embodiment, the thirdimpurity injection region 60 may be doped with a chalcogen element(i.e., a group 16 element) such as sulfur (S), selenium (Se), andtellurium (Te), or a metal element such as lead (Pb), titanium (Ti),tantalum (Ta), tungsten (W), and nickel (Ni). In this case, a defectlevel may be formed in the energy band gap of silicon, and thus thephotoelectric conversion efficiency may be increased.

In a method of manufacturing the light sensor 108, an ion implantationprocess may be performed in the step of FIG. 12 to form the thirdimpurity injection region 60. The other manufacturing processes may bethe same or similar as described with reference to FIGS. 20 to 22.

FIG. 26 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 26, a light sensor 109 may include a third impurity injectionregion 60 that is disposed adjacent to a deep trench isolation structureDTI in a substrate 1. The third impurity injection region 60 may bedisposed along a sidewall of the deep trench isolation structure DTI. Inan exemplary embodiment, the third impurity injection region 60 may bedisposed between the sidewall of the deep trench isolation structure DTIand a photoelectric converter including a first impurity injectionregion 8 and a second impurity injection region 4.

The other components of the light sensor 109 may be the same or similaras corresponding components of the light sensor 108 described withreference to FIG. 25. In a method of manufacturing the light sensor 109,a tilt ion implantation process may be performed to form the thirdimpurity injection region 60 after the substrate 1 is etched to form thedeep trench 3 in the step of FIG. 10. The other manufacturing processesmay be the same or similar as described with reference to FIGS. 20 to22.

FIG. 27 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 27, a light sensor 110 may include a third impurity injectionregion 60 that may be formed in a region adjacent to the second surface1 b and along the sidewall of the deep trench isolation structure DTI inthe substrate 1. The third impurity injection region 60 may be formed bytilt ion implantation after the formation of the deep trench 3 and byion implantation after the back grinding process on the second surface 1b. The other components and other manufacturing processes may be thesame or similar as described with reference to FIGS. 20 to 22 and 26.

FIG. 28 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 28, a light sensor 111 may include a light-shielding pattern 65disposed on the anti-reflection layer 42. The light-shielding pattern 65may be formed of a metal such as tungsten and may have a grid shape. Thelight-shielding pattern 65 may prevent crosstalk between neighboringunit pixel regions UP. The other components of the light sensor 111 maybe the same or similar as corresponding components of the light sensor105 described with reference to FIG. 20.

FIG. 29 is a partial cross-sectional view illustrating a light sensoraccording to an exemplary embodiment of the present inventive concept.

In FIG. 29, a light sensor 112 may include a light-shielding pattern 65that penetrates the anti-reflection layer 42 and the fixed charge layer40 into the deep trench isolation structure DTI. In this case, a bottomsurface of the light-shielding pattern 65 may be in contact with thedeep trench isolation structure DTI and a portion of the light-shieldingpattern 65 may be surrounded by the deep trench isolation structure DTI.The other components of the light sensor 112 may be the same or similaras corresponding components of the light sensor 111 of FIG. 28.

FIG. 30 is a partial cross-sectional view illustrating a light sensoraccording to an exemplary embodiment of the present inventive concept.

In FIG. 30, a light sensor 113 may include an amorphous structure 70that may be disposed adjacent to the second surface 1 b of the substrate1. The amorphous structure 70 may be an amorphous layer disposed on thesecond surface 1 b of the substrate 1. In this case, the second surface1 b may be lower than a top surface of the deep trench isolationstructure DTI. In an exemplary embodiment, the amorphous structure 70may include amorphous silicon.

In an exemplary embodiment, the amorphous structure 70 may be formed byamorphization of a portion of the substrate 1. The energy band gap ofsilicon in the substrate 1 may be reduced by the amorphous structure 70.Thus, the photoelectric conversion efficiency of the photoelectricconverter including the first impurity injection region 8 and the secondimpurity injection region 4 may be increased. For example, a laser maybe irradiated on a portion of the substrate 1 to make single-crystallinesilicon of the substrate 1 unstable, and then, an annealing process maybe performed on the unstable single-crystalline silicon of the substrate1 to amorphize the portion of the substrate 1. In an exemplaryembodiment, the annealing process may be performed in an ambient ofhydrogen gas.

The present inventive concept is not limited thereto. For example, theamorphous layer may be deposited on the second surface 1 b using aplasma-enhanced chemical vapor deposition (PECVD) method or aninductively-coupled-plasma chemical vapor deposition (ICP CVD) method.

The other components and other manufacturing processes may be the sameor similar as described with reference to FIGS. 20 to 22.

FIG. 31 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 31, a light sensor 114 may include an amorphous structure 70that may be disposed adjacent to the deep trench isolation structure DTIin the substrate 1. After the formation of the deep trench 3, theamorphous structure 70 may be formed by amorphization of a portion ofthe substrate 1 in the deep trench 3 or by depositing an amorphous layeron the inner wall of the deep trench 3. The other components and othermanufacturing processes may be the same or similar as described withreference to FIG. 30.

FIG. 32 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 32, a light sensor 115 may include an amorphous structure 70having a first amorphous structure 71 disposed along the sidewall of thedeep trench isolation structure DTI and a second amorphous structure 72disposed adjacent to the second surface 1 b of the substrate 1. Theother components and other manufacturing processes may be the same orsimilar as described with reference to FIGS. 30 and 31.

FIG. 33 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept.

In FIG. 33, a light sensor 116 may include a first unit pixel region UP1and a second unit pixel region UP2. A first filter 68 may be disposed onthe anti-reflection layer 42 of the first unit pixel region UP1. Asecond filter 73 may be disposed on the anti-reflection layer 42 of thesecond unit pixel region UP2. A planarization layer 44 may be disposedon the first filter 68 and the second filter 73. In an exemplaryembodiment, the first filter 68 and the second filter 73 may be colorfilters. In an exemplary embodiment, the first filter 68 may be a whitefilter without pigment. The second filter 73 may be a color filter witha color pigment added, to filter a specific color such as such as a redcolor, a blue color, and a green color.

In an exemplary embodiment, an infrared filter exists between the lens1001 and the light sensor 1003 in the image processing device 1000 ofFIG. 1, and thus only infrared light may be incident through the microlens 46. In this case, the infrared light may pass through both thefirst filter 68 and the second filter 73.

The present inventive concept is not limited thereto. For example, theinfrared filter need not exist between the lens 1001 and the lightsensor 1003 in the image processing device 1000 of FIG. 1. In this case,visible light may be incident through the micro lens 46. As a result, afiltering may be performed within the light sensor 116. For example, thefirst filter 68 may be an infrared filter, and the second filter 73 maybe a color filter into which a pigment is added. Only infrared light maybe incident into the substrate 1 by the first filter 68 in the firstunit pixel region UP1. Only visible light having a specific wavelengthmay be incident into the substrate 1 by the second filter 73 in thesecond unit pixel region UP2. The second unit pixel region UP2 may alsoincrease the absorption factor of visible light by the light splitter50.

The various light sensors according to exemplary embodiments of thepresent inventive concept have been described with reference to thedrawings. The various structures and the various manufacturing methodsdescribed above may be combined in various forms.

FIG. 34 is a cross-sectional view illustrating a light sensor accordingto an exemplary embodiment of the present inventive concept. FIGS. 35and 36 are circuit diagrams illustrating portions of light sensorsaccording to exemplary embodiments of the present inventive concept.

In FIGS. 34 and 35, a light sensor 200 may include a pixel substrate 210and a memory substrate 220 which are electrically connected to eachother. For example, the pixel substrate 210 may be electricallyconnected to the memory substrate 220 through a connection member 230.The connection member 230 may be, for example, a solder bump, and thepixel substrate 210 may be connected to the memory substrate 220 by aflip chip bonding method. However, the present inventive concept is notlimited thereto. For example, the pixel substrate 210 may beelectrically connected to the memory substrate 220 by a wire. In anexemplary embodiment, a through-via may electrically connect the pixelsubstrate 210 to the memory substrate 220. In an exemplary embodiment,the pixel substrate 210 and the memory substrate 220 may be connected toeach other by a hybrid bonding technique using a copper-copper (Cu-Cu)bonding technique.

In an exemplary embodiment, the pixel substrate 210 may be the same orsimilar as described with reference to FIGS. 1 to 33. The pixelsubstrate 210 may include a plurality of unit pixel regions UP. Thememory substrate 220 may include a plurality of unit memory regions MRelectrically connected to the plurality of unit pixel regions UP. Eachof the plurality of unit memory regions MR may include a capacitor CAP.A unit pixel region UP and unit memory region MR may combine to form aunit pixel 240. The pixel substrate 210 may be referred to as a firstsubstrate. The memory substrate 220 may be referred to as a secondsubstrate.

A circuit operation of the unit pixel region UP and the unit memoryregion MR will be described with reference to FIG. 35.

In FIG. 35, each of the plurality of unit pixel regions UP may include atransfer transistor TG, a pixel source follower transistor SFp, and apixel reset transistor RGp. A first source/drain of the transfertransistor TG may be connected to a photodiode PD, and a secondsource/drain of the transfer transistor TG may be connected to afloating diffusion region FD. Each of the unit memory regions MR mayinclude a sampling transistor SM, a memory reset transistor RGm, thecapacitor CAP, a memory source follower transistor SFm, and a memoryselection transistor SELm.

The pixel reset transistor RGp may be disposed between a first powersource Vd1 and the floating diffusion region FD. The pixel sourcefollower transistor SFp may be disposed between a second power sourceVd2 and the connection member 230. The memory reset transistor RGm maybe disposed between a third power source Vd3 and an electrode of thecapacitor CAP. The memory source follower transistor SFm may be disposedbetween a fourth power source Vd4 and a source/drain of the memoryselection transistor SELm.

When light is incident on the photodiode PD of the unit pixel region UPthrough the micro lens 46, electron-hole pairs (EHPs) may be generatedin proportion to energy of absorbed light. The transfer transistor TGmay be turned-on to transfer charges generated from the photodiode PD tothe floating diffusion region FD. Thus, the pixel source followertransistor SFp may be turned-on to transmit the charges to the unitmemory region MR through the connection member 230 (e.g., a solderbump). The sampling transistor SM may be turned-on to store the chargesgenerated in the unit pixel region UP. Thus, the charges may be storedin the capacitor CAP. The memory selection transistor SELm may beturned-on to sense the charges stored in the capacitor CAP. In FIG. 35,one unit pixel region UP is electrically connected to one unit memoryregion MR.

In FIG. 36, two unit pixel regions UP1 and UP2 are electricallyconnected to two unit memory regions MR1 and MR2 through one connectionmember 230. A predetermined number of the unit pixel regions UP1 and UP2connected to the one connection member 230 may range from 1 to 64. Inthis case, a distance between two adjacent connection members 230 may beincreased to increase a margin of a process for connecting fine unitpixel regions. Each of the unit pixel regions UP1 and UP2 may furtherinclude a pixel selection transistor SELp. With the control of the pixelselection transistor SELp and the sampling transistor SM, one of theunit pixel regions UP1 and UP2 may be selectively turned-on, and one ofthe unit memory regions MR1 and MR2 may be turned-on. Thus, chargesgenerated in one of the unit pixel regions UP1 and UP2 may be stored inthe one of the unit memory regions MR1 and MR2.

As described above, the light sensor 200 of FIG. 34 may further includethe memory substrate 220. Thus, the light sensor 200 may operate in aglobal shutter mode. In an exemplary embodiment, the light sensor 200may operate in a wide dynamic range (WDR) mode. The light sensor 200 mayfurther include an additional circuit for operating in the globalshutter mode or the WDR mode.

FIG. 37 is a schematic block diagram illustrating a light sensoraccording to an exemplary embodiment of the present inventive concept.

In FIG. 37, a light sensor 300 may include a sensor 310 formed in thepixel substrate 210 of FIG. 34, a memory part 320 formed in the memorysubstrate 220 of FIG. 34, and a data processor 330 processing electricalsignals stored in the memory part 320. For example, the electricalsignals may correspond to image data. In an exemplary embodiment, thedata processor 330 may be formed in the memory substrate 220 of FIG. 34.

In a global shutter mode, electrical signals (image data) generated inall of unit pixel regions UP of the sensor 310 of the light sensor 300may be stored in the memory part 320 at the same time. The dataprocessor 330 may sequentially sense the data stored in the memory part320 in the unit of row. Thus, the global shutter mode may be realized.

In a wide dynamic range (WDR) mode, the sensor 310 may receive light fora first time to generate charges and may store the generated charges inthe memory part 320. In addition, the sensor 310 may receive light againfor a second time to generate charges and may store the generatedcharges in the memory part 320. The first time may be longer than thesecond time. The data processor 330 may check and synthesize acorrelation between the data generated for the first time and the datagenerated for the second time. Thus, high-quality image data may beoutputted.

In the light sensor according to an exemplary embodiment of the presentinventive concept, the light splitter may be disposed at the focal pointof a micro lens to scatter light so that the multiple reflections occurto increase the light path within the sensor, and thus the absorptionfactor may be increased. Thus, the quantum efficiency may increase.

As a result, it is possible to increase the sensing sensitivity ofinfrared light which is less absorbed in the light sensor compared to avisible light.

In an exemplary embodiment of the present inventive concept, a lightsensor may include a photoelectric-conversion-enhancing layer thatserves to increase the photoelectric conversion efficiency of thephotoelectric converter. The photoelectric converter may include thefirst impurity injection region 8 and the second impurity injectionregion 4. For example, the amorphous structure 70 of FIGS. 30-32 or thethird impurity injection region 60 of FIGS. 25-27 may serve as thephotoelectric-conversion-enhancing layer. The amorphous structure may beformed of an amorphous silicon layer.

For example, the third impurity injection region 60 may be doped withimpurities of at least one of germanium (Ge), sulfur (S), selenium (Se),tellurium (Te), lead (Pb), titanium (Ti), tantalum (Ta), tungsten (W),and nickel (Ni).

While the present inventive concept has been shown and described withreference to exemplary embodiments thereof, it will be apparent to thoseof ordinary skill in the art that various changes in form and detail maybe made therein without departing from the spirit and scope of theinventive concept as defined by the following claims.

What is claimed is:
 1. A light sensor comprising: a first substrateincluding a plurality of unit pixel regions; a deep trench isolationstructure disposed in the first substrate, the deep trench isolationstructure isolating each of the plurality of unit pixel regions fromeach other; a plurality of photoelectric converters, each of theplurality of photoelectric converters being disposed in one of theplurality of unit pixel regions; a plurality of micro lenses disposed onthe first substrate; a plurality of light splitters disposed on thefirst substrate, each of the plurality of light splitters being disposedbetween one of the plurality of micro lenses and one of the plurality ofphotoelectric converters; and a plurality ofphotoelectric-conversion-enhancing layers, each of the plurality ofphotoelectric-conversion-enhancing layers is disposed between one of theplurality of light splitters and one of the plurality of photoelectricconverters.
 2. The light sensor of claim 1, further comprising: a fixedcharge layer in contact with the first substrate between each of theplurality of photoelectric converters and each of the plurality of microlenses.
 3. The light sensor of claim 1, further comprising: a pluralityof vertical-type gates disposed on the first substrate, each of theplurality of vertical-type gates extending from a surface of the firstsubstrate into the first substrate in one of the plurality of unit pixelregions.
 4. The light sensor of claim 1, wherein each of the pluralityof light splitters is disposed in a recessed region of each of theplurality of unit pixel regions of the first substrate, and wherein asidewall of each of the plurality of light splitters is inclined.
 5. Thelight sensor of claim 4, further comprising: a refractive indexdifference part disposed between the sidewall of each of the pluralityof light splitters and the deep trench isolation structure, wherein eachof the plurality of light splitters is a portion of the first substrateprotruding from the recessed region of the first substrate toward one ofthe plurality of micro lenses.
 6. The light sensor of claim 1, furthercomprising: an anti-reflection layer disposed between the firstsubstrate and the plurality of micro lenses; and a planarization layerdisposed between the anti-reflection layer and the plurality of microlenses, wherein the plurality of light splitters is disposed between theanti-reflection layer and the planarization layer.
 7. The light sensorof claim 6, wherein the plurality of light splitters includes a materialhaving a higher refractive index than silicon.
 8. The light sensor ofclaim 1, further comprising: an amorphous structure that is in contactwith a sidewall of the deep trench isolation structure.
 9. The lightsensor of claim 1, further comprising: an interlayer insulating layerdisposed on a bottom surface of the first substrate; and a reflectordisposed in the interlayer insulating layer.
 10. The light sensor ofclaim 1, further comprising: a second substrate electrically connectedto the first substrate and including a plurality of unit memory regions,wherein each of the plurality of unit memory regions stores datagenerated from one of the plurality of unit pixel regions.
 11. The lightsensor of claim 10, wherein each of the plurality of unit memory regionsincludes a capacitor.
 12. The light sensor of claim 10, furthercomprising: a plurality of connection members connecting the firstsubstrate to the second substrate.
 13. The light sensor of claim 12,wherein a predetermined number of unit pixel regions among the pluralityof unit pixel regions is electrically connected to each of the pluralityof connection members, and wherein the predetermined number ranges from1 to
 64. 14. The light sensor of claim 10, wherein the second substratefurther comprises a data processor processing electrical signals storedin the plurality of unit memory regions, wherein the plurality of unitmemory regions stores data of the plurality of unit pixel regions atsubstantially the same time; and wherein the data processor sequentiallysenses the data stored in the plurality of unit memory regions.
 15. Alight sensor comprising: a substrate having a first surface and a secondsurface opposite to the first surface including a plurality of unitpixel regions; a photoelectric converter disposed in each of theplurality of unit pixel regions of the substrate; a micro lens disposedon the second surface of the substrate overlapping one of the pluralityof unit pixel regions; a light splitter disposed between the micro lensand the photoelectric converter; and aphotoelectric-conversion-enhancing layer disposed between the lightsplitter and the photoelectric converter, wherein the light splitter isdisposed at a focal point of the micro lens.
 16. A light sensorcomprising: a substrate having an array of a plurality of unit pixelregions including a first unit pixel region and a second unit pixelregion, each of the plurality of unit pixel regions including aphotoelectric converter; a plurality of light splitters including afirst light splitter and a second light splitter, the plurality of lightsplitters being disposed on the substrate, the first light splitterbeing disposed at a first distance from a center of the first unit pixelregion and the second light splitter being disposed at a second distancefrom a center of the second unit pixel region, wherein the seconddistance is larger than the first distance; and a plurality of microlens including a first micro lens and a second micro lens overlappingthe first light splitter and the second light splitter, respectively,wherein a center of the first micro lens and a center of the secondmicro lens are directly above the center of the first unit pixel regionand the center of the second unit pixel region, respectively.
 17. Thelight sensor of claim 16, further comprising: a deep trench isolationstructure penetrating the substrate and defining each of the pluralityof unit pixel regions.
 18. The light sensor of claim 16, furthercomprising: a photoelectric-conversion-enhancing layer disposed withinthe first unit pixel region having a photoelectric converter, whereinthe photoelectric-conversion-enhancing layer is disposed between thefirst light splitter and the photoelectric converter.
 19. The lightsensor of claim 18, wherein the photoelectric-conversion-enhancing layerincludes an amorphous silicon layer.
 20. The light sensor of claim 18,wherein the photoelectric-conversion-enhancing layer includes animpurity injection region doped with impurities of at least one ofgermanium (Ge), sulfur (S), selenium (Se), tellurium (Te), lead (Pb),titanium (Ti), tantalum (Ta), tungsten (W), and nickel (Ni).